Conventional processes of manufacturing a shoe will be described briefly with reference to FIG. 1. First, in the step (a) a shoe upper 11 is formed by joining genuine leathers or synthetic leathers or the like. In the step (b) an inner sole 13 is attached to a wooden mold 12 by means of nailing and starching and the like.
Subsequently, in the step (c), the wooden mold is covered with the joined shoe upper 11, and a lower fringe portion of the shoe upper 11 is bent to be ready for joining to a peripheral region 13a of the inner sole 13. As a result of such work, the lower fringe portion of the shoe upper 11 is bent along the surface of the wooden mold 12. Further, the bent portion 11a of the shoe upper 11 is roughened so as to be adhered securely to a bottom sole in a subsequent step described below.
In the subsequent steps, different processes are carried out from each other in a VP manufacturing method and a CP manufacturing method. As an example of the subsequent processes, the CP manufacturing method will now be described. In the step (d) insert members such as a cushioning member 14 for protecting the arch of the foot and a member 15 for bending the front portion of the inner sole 13 are mounted on the inner sole 13. Further, in the step (e) a shoe bottom 16 formed of rubber and leather and the like is manufactured.
In addition, in the step (f) the shoe bottom 16 is adhered to the bent portion of the shoe upper 11 and the inner sole 13 by means of a pressure-applying machine. In general, an insert is placed in a space of the shoes formed by the inner sole 13 and the shoe upper 11 and the insert (not shown) is adhered to the upper surface of the inner sole 13. Thus, the manufacturing processes of the shoe is finished. However, in the conventional manufacturing processes of the shoe, in the step (b) the work to fasten the inner sole 13 to the wooden mold 12 was carried out by nailing or adhering or the like.
When the inner sole 13 is fastened to the wooden mold 12 by nailing, a nail is usually driven into two portions in a toe section and two portions in a heel section of the inner sole 13, respectively; as a result, four portions of the inner sole 13 are required to be fastened by nailing. After fastening of the inner sole 13 to the shoe upper 11 is completed, the four nails driven into the wooden mold 12 must be pulled out; thus, eight processes for pulling out the nails per pair of shoes are required.
In addition, when the inner sole is fastened to the wooden mold at an improper place of the wooden mold which deviates from the normal position, the nails driven into the wooden mold through the inner sole are required to be pulled out and the work for fastening the inner sole to the wooden mold is required to be carried out again after pulling out all nails. Further, there might be caused an accident of injuring due to the failure of the pulling out of the nails.
Also in the adhesion of the inner sole 13 to the wooden mold 12, in the same manner as nailing, the inner sole 13 is required to be adhered to the wooden mold 12 at four portions of the sole 13, namely, at the two portions of the toe section and the two portions of the heel section. After the inner sole 13 is secured to the shoe upper 11, the inner sole 13 is required to be stripped off from the bottom portion of the wooden mold 12, so that eight processes are required.
In addition, shoe makers need an adhering machine of high price that would cost, for example, ten million Yen each.
U.S. Pat. No. 3,166,771 to Kline et al. (Kline '771) discloses a means for magnetically retaining an insole and last in assembled alignment. Its FIG. 6 (not reproduced here) shows a pressure sensitive tape 42 that is to be secured to the inner surface of insole 32. A cooperating magnet 40 is contained in the last bottom 30. The present inventor has discovered drawbacks in the foregoing teaching of Kline '771.
In particular, the present inventor has discovered that the use of a magnetic tape such as tape 42 of Kline '771 requires the tape to be impracticably large in thickness in order to create the required force of attraction to hold the inner sole (or insole) in a predetermined position with respect to a last (or shoe mold). Typically, with commercially available material that can be expected to be formed into the shape of such tape having a width of roughly 20 to 30 millimeters (as can be expected from FIG. 6 of Kline '771), the thickness of the tape reaches as large as roughly 20 to 30 millimeters. Such a thick tape is more appropriately referred to as a strip. Such a thick tape (or strip) poses the major problem of introducing a gap between the inner sole and the mold or last along the periphery thereof, which gap further renders the use of an automatic joining machine impractical. When an automatic joining machine is working to join one part of the inner sole along its periphery, the other portion of the inner sole directly opposite to said portion moves farther away from the bottom surface of the wooden mold, because the thick tape works like a pivot, thereby rendering the joining process impossible.
On the other hand, when the thickness of such tape is made thin enough, for example, less than roughly 0.1 to 0.5 millimeters in thickness which value may be required to prevent a bump in the insole and to make the existence of the tape unnoticeable so as to prevent the shoe from irritating the foot of a person wearing the shoe, the total attractive force provided by such tape is too small to hold the insole or inner sole in the designated position. This is especially so when the whole assembly of insole and last is turned upside down for being subjected to a subsequent process of joining by an automatic machine.
Additionally, the present inventor has discovered that a practical magnetic tape, which must have a relatively large thickness to hold the weight of the inner sole itself, must be removed after the whole manufacturing process is completed so as not to irritate the foot of a person wearing the shoe.
Furthermore, such a thick tape (or strip) poses another drawback for the purpose of providing a simplified system and method for the manufacture of shoes. This occurs when the magnetic attractive means (e.g., strip) is left in a completed shoe. A bump is then introduced in the surface of the inner sole that is directly adjacent the foot of a wearer of the shoe. The wearer's foot is then subjected to irritation caused by the bump.
Additionally, according to the teaching of Kline '771, a cumbersome additional process of attaching the magnetic tape to the insole at each time of production is required. A further problem is the necessity of extra space for storing the magnetic tape. An additional problem is the necessity to carefully align the magnetic tape with the corresponding, magnetically attractive counterparts provided in the bottom surface of the last; this is particularly necessary in view of the great decrease in magnetic force caused by a misalignment.